1. Field of the Invention
The present invention relates to an optical connector plug, an optical connector plug connecting method, an optical fiber cross-connection apparatus, an optical fiber cord retracting method, an optical fiber cord retraction device, and an optical connector plug alignment block all used in a cross-connecting operation in an optical network that is performed by automatically connecting or disconnecting optical fibers through the optical connector plugs by using a handling device.
2. Description of the Related Art
An optical fiber cross-connection apparatus connects or disconnects given optical fibers in a group of operated-side optical fibers to and from a group of stationary-side optical fibers. One such optical fiber cross-connection apparatus that auto-mates the optical cross-connecting operation by using a handling device has been proposed in Japanese Patent Application Laid-open No. 7-318820 (1995). In this optical fiber cross-connection apparatus, the handling device connects and disconnects optical connector plugs connected to front end portions of optical fiber cords by freely moving in a three-dimensional space through a moving means that is movable in an X-direction along a horizontal plane, in a Y-direction perpendicular to the X-direction and along the horizontal plane and in a Z-direction along a vertical direction.
A schematic plan view of a conventional optical fiber cross-connection apparatus is shown in FIG. 33 and its side view in FIG. 34. In FIG. 33 and FIG. 34, the optical fiber cross-connection apparatus 100 has a connection block 103, an optical connector plug alignment block 104, a handling system 105, an actuating system 108, an optical fiber cord retraction device 106, and a redundant cord storage unit 107. The connection block 103 has a plurality of optical adapters 111 for connecting optical connector plugs 110, each joined with an optical fiber cord 101 on an output side, to optical connector plugs 109 each joined with an optical fiber cord 102 on an input side. The optical connector plug alignment block 104 is arranged to oppose the connection block 103 and has an array of support holes to hold the optical connector plugs 109 of the input-side optical fiber cords 102 in a predetermined alignment. The handling system 105 holds an optical connector plug 109 to draw out the optical fiber cord 102 from the optical connector plug alignment block 104 and connects and disconnects the optical connector plug 109 to and from the optical adapter 111. The actuating system 108 moves the handling system 105 to a given position on the connection block 103 and the optical connector plug alignment block 104. The optical fiber cord retraction device 106 retracts rearwardly of the optical connector plug alignment block 104 the optical fiber cord 102 whose optical connector plug 109 was pulled out of the optical adapter 111. The redundant cord storage unit 107 accommodates the optical fiber cord 102 being retracted.
The optical fiber cord retraction device 106 has a retraction roller 106a that carries the input-side optical fiber cords 102 and an idle roller 106b disposed above the retraction rollers 106a and moved along the axis of the retraction roller 106a by the actuating system 108.
The conventional optical fiber cross-connection apparatus 100 cross-connects of optical fiber cords in the following steps. First, optical fiber cords 102 whose optical connector plugs 109 were disconnected from the optical adapters 111 in the connection block 103 by the handling system 105 are retracted rearward of the optical connector plug alignment block 104 by the retraction roller 106a and the idle roller 106b of the optical fiber cord retraction device 106 toward the redundant cord storage unit 107 which accommodates the cord. At the same time, the optical connector plugs 109 joined at the ends of the optical fiber cords 102 are received in a predetermined alignment into the support holes in the optical connector plug alignment block 104.
When the optical connector plugs 109 received in the optical connector plug alignment block 104 are moved to the connection block 103, a given optical connector plug 109 of an optical fiber cord 102 is pulled out of the optical connector plug alignment block 104 by the handling system 105 through the actuating system 108 and is set to face a given optical adapter 111 on the connection block 103 and inserted to it, thus completing the cross-connection of the optical fiber cord 102.
In the conventional optical fiber cross-connection apparatus, there is a room for further improvements as follows. That is, in an optical network, when it is desired to minimize adverse effects of a reflected light produced as a result of inserting an optical module, angled physical contact (APC) optical connector plugs are used which have their connecting end surface polished at a predetermined angle to a plane perpendicular to a light axis. Thus, where the APC optical connector plugs are used on the conventional optical fiber cross-connection apparatus, since optical connector plugs need to be connected such that their connecting end surfaces contact each other in a parallel state, the attitudes of the optical connector plugs as they are inserted into the connection block are not uniquely determined. This makes it difficult to apply the conventional structure as is to the APC optical connector plugs.
Further, when an optical connector plug is inserted into the optical adapter with the plug attitude rotated from a connection attitude in which the optical connector plug can be connected or when the optical connector plug inserted in the optical adapter is applied a rotating force, expected optical characteristics, such as a desired insertion loss, may not be obtained.
There is another problem with the conventional optical fiber cross-connection apparatus. When an optical connector plug is pulled out from the optical adapter of the connection block by a handling device and its optical fiber cord is retracted by the optical fiber cord retraction device to be accommodated in the redundant cord storage unit, a flange of the optical connector plug may get entangled and caught by other cords, rendering a normal retraction of the cord impossible.
Further, the conventional optical fiber cross-connection apparatus or the optical fiber cord retraction device has the following problem that needs to be addressed. That is, optical fiber cords are subjected to repetitive retracting operations as they are retracted back toward the redundant cord storage unit by the optical fiber cord retraction device and also to repetitive feeding operations as the optical connector plugs are drawn forward from the optical connector plug alignment block by the handling system. Thus, the optical fiber cords may develop persisting physical distortions, such as twists and bends. Therefore, if the optical fiber cords are moved forward and backward by holding them between the retraction roller and idle roller, they may get dislocated from between the retraction roller and idle roller due to their physical distortions, such as twists and bends.
Further, depending on a distance between the provided positions of the optical connector plug alignment block and the redundant cord storage unit, the optical fiber cords that are being retracted by the optical fiber cord retraction device into the redundant cord storage unit may not be normally accommodated into the unit.